Phyllospheric Mycoflora of Sugarcane (Saccharum officinarum L.) in Ambedkar Nagar District, U.P. Diversity, Seasonal Dynamics, Ecological Analysis, and Disease Risk Assessment

Abstract

The phyllosphere of sugarcane (Saccharum officinarum L.) in Ambedkar Nagar district, Uttar Pradesh, India was systematically investigated for phyllospheric mycofloral diversity, percentage frequency, percentage abundance, and seasonal dynamics over ten months (June 2022 – March 2023) across nine development blocks. A total of 30 fungal species belonging to 14 genera across three taxonomic classes — Deuteromycetes (86.7%), Zygomycetes (10.0%), and Basidiomycetes (3.3%) — were isolated using the leaf wash technique on antibiotic Potato Dextrose Agar (PDA) at 28°C. Annual grand total colony count was 1,895 CFU, peaking at 339 CFU in October (post-monsoon). Aspergillus niger and A. flavus jointly achieved the highest percentage frequency (87.5%), while Aspergillus dominated abundance at the genus level (28.18%). Annual pathogenic colony proportion was 22.8%. A novel Disease Risk Index (DRI) reached 24.3 (Very High) in October–November. A highly significant positive correlation was established between phyllospheric Colletotrichum falcatum colony counts (October) and field red rot incidence (November–December) across 18 field sites (r = +0.91, p < 0.01). The presence of Trichoderma viride and T. harzianum in the phyllospheric community was documented, with a Biocontrol Adequacy Index (BAI) of 0.68, indicating the need for augmentative biocontrol. The investigation provides the first comprehensive phyllospheric mycological database for Ambedkar Nagar sugarcane and proposes a district-level early warning framework for fungal disease management.